Just a question (and my apologies if you've already answered this either on this thread or elsewhere): Where and how, exactly, did you find this survey?
Did you just Google "Marriott survey" and this is one of the things that turned up?
Normally, I would expect a survey like this to be entered either from the Marriott site, or from some reputable survey site. If it was found all by itself, just floating free, disconnected from one of those "normal" entry portals, I wouldn't expect to get any points from it.
On the other hand, I'm not that worried about someone, knowing ONLY my MR number and no other identifying information, somehow dipping into my account and stealing my billions and billions of MR points either. (Full disclosure: having recently done a redemption, I have fewer than 300 MR points anyhow.
)
One other thing (again, apologies if already discussed): Those who are investigating this might also consider contacting the owner of Linescale, Larry Weiss. Contact info here:
http://www.linescale.com/web/callme.htm
I'm sure he could shed some light on this mystery!